How to Calculate How Long a 9 Volt Battery Will Last

A Typical 9-Volt Battery (Note The Side-By-Side Terminals)
••• nine volts alkaline battery on table image by JoLin from

Known originally as "PP3" batteries, rectangular 9-volt batteries continue to be very popular with designers of radio-controlled (RC) toys, digital alarm clocks and smoke detectors. Like 6-volt "lantern" models, 9-volt batteries actually consist of a plastic outer shell that encases several small, cylindrical cells wired in a series. However, 9-volt batteries use different types of a cells (e.g. alkaline, lithium, nickel-cadmium), which have different output capacities To calculate the approximate lifetime of a battery powering a specific appliance, you simply need to know the appliance's power rating and the battery's capacity.

    Determine the power rating (in watts) for the appliance using the battery. In general, this information is printed on a label on the bottom or rear of the device. If you're not sure, visit the manufacturer's website, pull up the device's model number and search under "Technical Specifications."

    Divide the power rating by 9 volts. The result will be the number of amperes or "amps" that the appliance draws from the battery.

    Find the "capacity" for the 9-volt battery by checking the Technical Specifications section of the battery's packaging. Note: the battery's capacity will most likely be measured in milliampere-hours or "mAh."

    Divide the battery's capacity by 1000 to convert its units to ampere-hours or "AH."

    Divide the battery's AH capacity (from Step 4 ) by the amps drawn (from Step 2). The result is the amount of time (in hours) that the battery will be able to power the appliance.

Related Articles

How to Calculate Millivolts to Amps
How to Calculate AH for a Battery
How to Calculate 30 KW to Amps
Button Battery Cross Reference Guide
How to Calculate Power Rating
How to Convert Reserve Capacity to Amp Hours
How to Calculate the Field Current in a DC Motor
How to Calculate How Long a Battery Will Last
How to Convert Horsepower to Foot Pounds
How to Get 12 Volts From a 48 Volt Golf Cart
How to Run Your Fridge on Solar Power
How to Convert HP to BTU/hr
How to Calculate the Volume of Water to Fill a Rectangular...
How to Calculate MBH
How to Convert HP to KVA
How to Figure kW Rating of a 3 Phase Electric Motor
How to Calculate Magnification on a Light Microscope
How to Choose Proper Heater Sizes for Motor Starters
How to Calculate Transformer VA Rating
How to Calculate Battery Watt-Hours